Male Fertility Genes in Bread Wheat (Triticum aestivum L.) and Their Utilization for Hybrid Seed Production

Abstract

Hybrid varieties can provide the boost needed to increase stagnant wheat yields through heterosis. The lack of an efficient hybridization system, which can lower the cost of goods of hybrid seed production, has been a major impediment to commercialization of hybrid wheat varieties. In this review, we discuss the progress made in characterization of nuclear genetic male sterility (NGMS) in wheat and its advantages over two widely referenced hybridization systems, i.e., chemical hybridizing agents (CHAs) and cytoplasmic male sterility (CMS). We have characterized four wheat genes, i.e., Ms1, Ms5, TaMs26 and TaMs45, that sporophytically contribute to male fertility and yield recessive male sterility when mutated. While Ms1 and Ms5 are Triticeae specific genes, analysis of TaMs26 and TaMs45 demonstrated conservation of function across plant species. The main features of each of these genes is discussed with respect to the functional contribution of three sub-genomes and requirements for complementation of their respective mutants. Three seed production systems based on three genes, MS1, TaMS26 and TaMS45, were developed and a proof of concept was demonstrated for each system. The Tams26 and ms1 mutants were maintained through a TDNA cassette in a Seed Production Technology-like system, whereas Tams45 male sterility was maintained through creation of a telosome addition line. These genes represent different options for hybridization systems utilizing NGMS in wheat, which can potentially be utilized for commercial-scale hybrid seed production.

Proteomic and Phosphoproteomic Analyses Reveal a Complex Network Regulating Pollen Abortion and Potential Candidate Proteins in TCMS Wheat

“…During the enriched biological process (BP) in the differentially expressed proteome and phosphoproteome data, pollen exine formation and sporocyte differentiation were the significantly down-regulated terms. The synthesis and transport of sporopollenin and the development of pollen exine structure are crucial to wheat fertility [ 21 , 22 ]. Sterile rice mutants lack sufficient sporopollenin to deposit exine, and thus pollen walls cannot be thickened to a normal extent [ 23 ].…”

CRISPR/Cas9-mediated disruption ofCjACOS5confers no-pollen formation on sugi trees (Cryptomeria japonicaD. Don)

“…Male sterility in a variety of crops (maize, rice, wheat, etc.) has helped produce hybrid seeds more efficiently than before [42][43][44] . Using genome editing technology, it is possible to turn a plant species with pollen into pollen-free varieties, even if wild pollen-free mutants had never been found in the same plant species.…”

CRISPR/Cas9-mediated disruption of CjACOS5 confers no-pollen formation on sugi trees (Cryptomeria japonica D. Don)

“…Male sterility in a variety of crops (maize, rice, wheat, etc.) has helped produce hybrid seeds more efficiently than before 43 – 45 . Using genome editing technology, it is possible to turn a plant species with pollen into pollen-free varieties, even if wild pollen-free mutants had never been found in the same plant species.…”